Apparatus for purifying gases



July 14, 1925. 1,545,703

J. A. SHAW APPARATUS FOR PURIFYING GASES bri' inai Filed Dec. 8. 1921 'Patentecl July 14, 1925.

UNITED STATES.

PATENT oEFIcE.

JOSEPH SHAW, or PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THE xorrnas COMPANY, or PITTSBURGH, PENNSYLVANIA, A oonPoRATIoN OF. PE NSYLVANIA.

APPARATUS FOR P URIFY IN G GASES.

Original application filed December 8, 1921, Serial No. 520,789. Divided and this application filed May 23, 1924. Serial No. 715,363.

To all whom it may concern:

Be it known that I, JOSEPH A. s]E [A\V, a citizen of the United States,.res1d1ng in Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Apparatus for- Purifying Gases, of which the following is a specification.

This invention relates to the removal of hydrogen sulphideand other noxious constituents, such as hydrocyanic acid, from gases containing them. Objects of the invention are to provide an apparatus for effecting an eflicient purification of the gases by means of an absorbent liquid which removes the noxious constituents, combined with revivification of the absorbent liquid by subsequent treatment that removes substantially all the absorbed sulphur in a solid form, whereby the escape of noxious fumes into the atmosphere in the vicinity of the gas purifying plant is avoided.

In addition to the general objects recited above, the invention has for further objects such other improvements or advantages in operation and results as are found to obtain in the processes and apparatus hereinafter described or claimed.

In the accompanying drawing forming a part of this specification and showing, for purposes of exemplification, a preferred form 'and manner in which the invention may be embodied and practiced, but without limiting the claimed invention specifically to such illustrative instance.

The figure illustrates the apparatus for carrying outthe improved gas purifying process of the present invention.

In its present embodiment, the invention is applied to the purification of fuel gases, such as coke oven gas. For convenience, :the present description will be confined to this important application of the invention. Features of the invention are, however, readily susceptible of other valuable applications; consequently, the invention is not confined in its scope to the specific use and embodiment herein described as an illustrative example.

In carrying out the inventiomthe gases,

after the tar and ammonia have been removed, are brought into contact with an absorbent agent constituted of a purifying solution. which is alkaline in reaction, for example: a sodium carbonate solution. The concentration of the solution may be varied as desired; in practice, a one to five per cent solution of" sodium carbonate will be found satisfactory. The gasestobe purified enterthe bottom of the scrubber or washer A, through a gas line 1 and discharge from the top of said scrubber through the purified-gas line 2. The purifying solution is delivered to the top of the scrubber A through the solution line 3 and the solution containing the absorbed im'pn'ri-' ties discharges from the bottom of saidscrubber through a line 4:. In the SCIlllJbGl, the'solution absorbs the hydrogen sulphide and other noxious constituents of the gases, forming soluble sulphide compounds, such as sodiu'm hydrogen sulphide. Carbon dioxlde, if present in the gas, is also absOrbed.

In accordance with the invention, the resulting fouled solution from the absorber A, is regenerated by. effecting contact of such fouled solution with a bed of an iron compound having an affinity for sulphur.

A suitable iron compound for this purpose is iron oxide. The apparatus for such regenerative treatment of the fouled solution is illustrated in the accompanying drawing and consisits of a sand filter B, of any of the ordinary types, such as are employed in water purification. A filter of this type is constituted essentially of a tank with supporting grids near the bottom. On the grids, a layer of course pebbles is laid, and on these, finer pebbles, then fine sand.

Above or below the grids a number of per forated air pipes are provided. For the present purposes, a bed of iron oxide may be of the respective filters are supplie tion is then ready to purify more gas in the i absorber or scrubber A.

In practice, it ispreferable to employ a number of filters B. Three of such filters are shown in the drawing. The spra pipes from branch pipes 12 provided with individual controlling-valves-and leading from a manifold 13 that is connected with the fouled solution discharge line 4:. An air manifold 14 is connected with branch pipes 15 having similar controlling-valves. The regenerated solution from the several filters discharges through branch line 16 into the return solution line 10. In the operation of the sys .tem, when the bed of iron oxide in any one tank is well. sulphided, the fouled liquor;

inlet is shut off, and the air is turned on at thebottom. This aeration converts the iron sulphide to iron oxide and to free sulphur, so that the bed is ready to treat further quantities of fouled liquor. w

The chemical reactions taking place in the absorption stage may be exemplified'by the following equations:

'(a) Absorption of hydrogen sulphide by sodium carbonate:

(6) Carbon dioxide, ifv present, is also (0) Hydrocyanic acid, if present, is also absorbed Na C O +HON=NaCN+ NaHCO The chemical reaction in the filters may be exemplified by the following equation:

Conversion of iron oxide to iron sulphide and regeneration of the alkali:'

The chemical reaction during aeration of the iron sulphide 'in the filters is substantially as follows:

Oxidation of iron sulphide to iron oxide and free sulphur:

- -accor-ding 150- .the following equation:

By aerating the clear alkaline liquor, sodium bicarbonate is converted tocarbonate,

- 2NaHCO :Na OO +GO -{-H O "The invention as hereinabove set forth tially as specified.

3. An apparatus for effectin purification may be variously embodied within the scope of the claims hereinafter made.

. This application isa division of my prior application for Letters Patent of the United I States for apparatus and process for purifying gases, filed December 8, 1921, Serial No 520,789.

I claim:

gases embodying: an absorber in which the gas to be purified is brought into contact with a liquid purifying agent; a plurality of filter beds each adapted to receive fouled purifying agent discharged from said ab,

sorber; manifold circulation "means interposed between said filter beds and said absorber, said, circulation means includin I valve devices for controlling thev individua 1. Apparatus for efiecting purification of fiow of the discharged purifying agent through individual filt'er beds; and an air manifold provided. with individual connections to individual filter beds and with valve 1 devices for individuallycontrolling the flow of air into individual filter beds; substantially as specified.

2. Apparatus for effecting purification of gases embodying: an absorber in which the gas to be purified is brought into.contact with a liquid purifying agent; a plurality of filter beds each adapted to receive fouled purifying agent discharged from said absorber; manifold circulation means interposedbetween said filter beds and said ab sorber, said circulation means including valve devices for controlling the individual flow of the discharged purifying agent through individual. filter beds and sprays mounted over thefilter beds; and an air manifold rovided with individual connections to in ividual filter beds and with valve devices 'for individually controlling the flow of air .into individual filterbeds; substanof gases embodying: an absor er in which the gas to be purified is brought into contact with a liquid purifying agent; filter bed means adapted to receive fouled purifying agent discharged from said absorber; circulation means interposed between said filter bed means and said absorber, said circulation means. including valve devlces. for

controlling the flow .of the discharged purifying agent through said filter bed means; and air supply means provided with connections to said filter bed means and with valve devices for controlling the flow of air into said filter bed means; substantially as specified. v

4. An apparatus-for effecting purification of gases embodying: an absorberin which v the gas to be purified is brought into convtact with a liquid purifying agent; filter bed means adapted to receive fouled purifying agent discharged from said absorber; circulation means interposed between said filwith connections to said filter bed means and ter bed means and said absorber, said circuwith valve devices for controlling the fl'ow lation means including valve devices for of air into said filter bed-means; substan- 10 controlling the flow of the discharged puritially as specified. 5 fying agent through said filter bed means In testimony whereof I have hereunto set and spray means mounted over said filter my hand.

bed means; and air supply means provided JOSEPH A. SHAW. 

